1. Field of the Invention
The present invention relates to an image display apparatus using an electron-emitting device.
2. Related Background Art
A flat panel display which arranges many electron-emitting devices as electron sources on a planar substrate, irradiates an phosphor of an imaging member on a substrate with an electron beam emitted from an electron source on the opposite side to make the phosphor emit light and display images, needs to keep the inside of a vacuum chamber including the electron source and the imaging members into a high vacuum. This is because when a gas is generated in the vacuum chamber and the pressure increases, the gas adversely exerts an adverse effect on the electron sources to decrease an electron emission amount and hinder the display of a bright image, though the extent of the effect depends on the types of the gas.
Gases generated from image display members accumulate in the vicinity of an electron source before reaching a getter installed outside an image display area, locally increase pressure and deteriorate the electron source, which is a peculiar problem particularly to a flat panel display. Japanese Patent Application Laid-Open No. H09-82245 describes a method of arranging the getter in an image displaying region and making it immediately adsorb the generated gases to inhibit the deterioration and damage of elements. In addition, Japanese Patent Application Laid-Open No. 2000-133136 shows a configuration in which a non-evaporable getter is arranged in the image displaying region, and a evaporable getter is arranged outside the image displaying region. Furthermore, Japanese Patent Application Laid-Open No. 2000-315458 shows a method of performing a series of operations including degassing, getter forming and seal bonding (making a chamber into a vacuum) in an evacuating chamber.
There are a evaporable getter and a non-evaporable getter in getters. The evaporable getter has an extremely high speed of eliminating water and oxygen, but has a speed close to zero of eliminating an inert gas such as argon (Ar), as well as the non-evaporable getter has. Argon gas is ionized by an electron beam to become positive ions, which are accelerated in an electric field for accelerating electrons, and bombard the electron source to damage the electron source. The positive ions further may discharge inside the vacuum chamber and damage an apparatus.
On the other hand, Japanese Patent Application Laid-Open No. H05-121012 describes a method of connecting a sputter ion pump to a vacuum chamber of a planar display and keeping the vacuum chamber into a high vacuum for a long time. However, the planar display needs a strong magnet, and then a magnetic field deflects an electron orbit of the display and may affect images.